RHAIENG-948: fix(ppc): build failure due to missing numpy in aipcc wheel index

```
+ pip install --no-cache-dir -r requirements.txt
  Looking in indexes: https://console.redhat.com/api/pypi/public-rhai/rhoai/3.0/cpu-ubi9/simple/
  ERROR: Could not find a version that satisfies the requirement numpy>=1.22 (from versions: none)
  ERROR: No matching distribution found for numpy>=1.22
  subprocess exited with status 1
```

Author: jiridanek

jupyter/datascience/ubi9-python-3.12/Dockerfile.cpu

@@ -231,7 +231,8 @@ if [ "${TARGETARCH}" = "ppc64le" ]; then
     cd onnx
     git checkout ${ONNX_VERSION}
     git submodule update --init --recursive
-    pip install --no-cache-dir -r requirements.txt
+    # aipcc index does not have numpy>=1.22
+    pip install --no-cache-dir --extra-index-url https://pypi.org/simple -r requirements.txt
     CMAKE_ARGS="-DPython3_EXECUTABLE=$(which python3.12)"
     export CMAKE_ARGS
     pip wheel . -w /root/onnx_wheel

jupyter/datascience/ubi9-python-3.12/Dockerfile.konflux.cpu

@@ -233,7 +233,8 @@ if [ "${TARGETARCH}" = "ppc64le" ]; then
     cd onnx
     git checkout ${ONNX_VERSION}
     git submodule update --init --recursive
-    pip install --no-cache-dir -r requirements.txt
+    # aipcc index does not have numpy>=1.22
+    pip install --no-cache-dir --extra-index-url https://pypi.org/simple -r requirements.txt
     CMAKE_ARGS="-DPython3_EXECUTABLE=$(which python3.12)"
     export CMAKE_ARGS
     pip wheel . -w /root/onnx_wheel